The present invention relates generally to a method and system of magnetic resonance (MR) imaging, and more particularly, to a method and system of multiple field-of-view (FOV) imaging.
Intravascular magnetic resonance (MR) methods for imaging arterial walls with ultra-high resolution for plaque characterization are widely known. It is also well known that intravascular MR has superior contrast and resolution of the vessels and the vessel wall compared to that provided by other known intravascular imaging methods, such as, intravascular ultrasound and angioscopy.
To be able to accurately and fully utilize these benefits, visualization of the interventional device placement and the surrounding anatomy, with frequent updates, is essential. Percutaneous placement of the interventional devices, currently, is performed under x-ray fluoroscopy. This requires the presence of an x-ray fluoroscopy and an MR scanner in the same room, with a compatible table. The disadvantages are numerous and include: alternating between two imaging modalities can alter the position of the catheter; it is quite costly; and both the patient and the physician are exposed to harmful ionizing radiation. An MR fluoroscopy technique to visualize interventional procedures with high spatial and temporal resolution is therefore desirable.
Many innovative techniques have been developed to make MR-guidance of interventional procedures possible. Known techniques focus on actively tracking the tip of the interventional device. Despite excellent temporal resolution, the drawback is that the number of device points that can simultaneously be tracked is limited by the number of receiver channels available on the scanner, which may not be sufficient for steering guidewires in the complex vasculature, or for selectively targeting small vessels. In many cases, visualization of the entire catheter is desirable to ensure there is no buckling or folding. Furthermore, these techniques rely on a previously acquired roadmap image to aid in localization, which does not necessarily represent the anatomy accurately because of motion, and additional roadmap images may be acquired throughout the procedure.
Known methods combine interventional device and anatomical roadmap images from multiple channels, during MR guided interventional procedures. The combined image feature dynamic roadmap images, as well as interventional device images. However, this implementation does not allow independent control over each channel""s data, and signal from interventional devices may be obscured by the higher signal from the surface coil when roadmap images from surface coils are combined with interventional device images that have lower signal content.
It would therefore be desirable to design an intravascular magnetic resonance system and method that allows independent control over each of a number of data channels to provide interventional device as well as anatomical mapping at a clinically useful frame rate.
The present invention provides a system and method of multiple field-of-view magnetic resonance imaging that overcomes the aforementioned drawbacks.
In accordance with one aspect of the present invention a method of real-time multiple field-of-view imaging is disclosed. The method includes acquiring a number of imaging data sets each including a plurality of imaging space data lines organized in a semi-bit-reversed pattern. Next, at least one image frame factor having an imaginary part and a real part is determined from the plurality of reorganized imaging space data lines. An image is then constructed from at least one image frame factor.
In accordance with another aspect of the present invention, a computer program to generate real-time multiple field-of-view images causes a computer to acquire imaging data having a plurality of k-space lines. When instructed, the computer program reorders the plurality of k-space lines in a semi-bit-reversed order and determines a real part and an imaginary part of each of the plurality of reordered k-space lines. Using the real part and the imaginary part of each of the plurality of reordered k-space lines, the computer program determines at least one image factor frame and constructs an image therefrom.
In accordance with yet another aspect of the present invention, a multiple field-of-view imaging system is disclosed. The system includes a number of data acquisition devices and a data processing workstation having a computer readable storage medium having thereon at least one computer program. The system further includes a data transfer interface configured to transfer imaging data from the data acquisition devices to the data processing workstation. A data receiver having at least one device channel and at least one mapping channel is further provided.
The computer program provided with the multiple field-of-view image system instructs the data acquisition device to acquire imaging data having a plurality of imaging lines in a semi-bit-reversed phase-order and to transfer that data to the data processing workstation via the data transfer interface. The computer program then causes the data processing workstation to reorder the plurality of imaging lines according to the semi-bit-reversed order and to determine a real and imaginary part of each of the plurality of reordered imaging lines. At least one image factor frame is then determined and used to reconstruct a magnetic resonance image.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.